1. Field of the Invention
The invention generally relates to a vaccine for hookworm. In particular, the invention provides vaccines based on parasite-derived antigens.
2. Background of the Invention
Hookworm infection is a significant public health concern in developing countries around the world, causing enteritis, intestinal blood loss, anemia, developmental delays, and malnutrition. It is estimated that there are more than one billion cases of human hookworm infection worldwide, with 194 million cases in China alone (Hotez et al. 1997). In some regions of China such as Hainan Province in the South China Sea more than 60 percent of the population harbors hookworms (Gandhi et al. 2001).
Most of the pathology caused by hookworm results from the adult stages of the parasite in the human intestine. The attachment of adult Ancylostoma and Necator hookworms to the mucosa and submucosa of the vertebrate small intestine is one of the best-defined examples of host-parasite relationships in all of parasitology. Comprised of several cubic millimeters of host mucosal and submucosal tissue lodged in the buccal capsule of the parasite, it is possible to actually touch the host-parasite relationship at necropsy or autopsy (Kalkofen, 1970; Kalkofen, 1974).
The dog hookworm Ancylostoma caninum is a major cause of morbidity and mortality in dogs throughout the world including subtropical regions of North America. Hookworm-associated blood loss leading to severe anemia and even death can occur in dogs between 2 and 3 weeks after a single primary infection (Soulsby, 1982; Jones and Hotez, 2002). Significantly, A. caninum has also been recently identified as an important human pathogen. Zoonotic infection with one adult A. caninum parasite can result in eosinophilic enteritis syndrome, an inflammatory condition of the intestine in response to invasion by the parasite (Prociv and Croese, 1990). The pathogenesis of A. caninum infection is associated with the intestinal blood loss that occurs during adult worm attachment and feeding in the mammalian small intestine (Kalkofen, 1970; Kalkofen, 1974).
Current efforts for the treatment and control of hookworm infestations are limited to periodic removal of adult hookworms from patients with anthelmintics. This approach has several limitations, including rapid reinfection following treatment, requiring multiple visits, and the eventual development of anthelmintic resistant strains of hookworms following several years of heavy anthelmintic treatments (Savioli et al. 1997; Geerts and Gryseels, 2000). Thus, it would be of great benefit to have available additional methods for both treating and preventing hookworm infection in mammals. For example, it would be highly advantageous to have available vaccines to treat or prevent hookworm infection.